Apple has said it will "one day" end its reliance on mined materials in its products as it looks to boost recycling of old phones.
In its annual environmental report the tech giant said: "We believe our goal should be a closed-loop supply chain, where products are built using only renewable resources or recycled material."
Work is already underway, it said, on increasing the amount of recycled material used in new phones, with the California-based company trialling new disassembly robots to improve the company's ability to reclaim used materials.
Phones currently use minerals drawn from sources across the world for parts, including tungsten, tantalum, gold and cobalt. Often the supply chains for these resources stretch back to conflict-riven countries or states where environmental protections are not well enforced.
Other phone manufacturers have also woken up to the need to reduce the amount of waste and pollution associated with devices as well as the potential for so-called conflict minerals to be used unwittingly in manufacturing.
For instance, niche manufacturer Fairphone aims to trace the supply chain of all of the materials used in its devices and has pursued a modular design to make recycling easier.
Apple said it would take "many years" for it to realise the ambition.